The present invention relates generally to the field of railroad freight cars for carrying standardized intermodal cargo containers. In particular, the present invention relates to a retractable container stop which prevents the longitudinal shifting of containers in a railroad freight car well. The present invention may preferably be used with a retractable container guide which acts in conjunction with the container stop by deflecting cargo containers into position as they are loaded into the railroad freight car well.
The transportation of intermodal containers on railcars has been a common practice for several decades. The sizes and capacities of the containers have steadily increased in time. Intermodal cargo containers have been standardized in various lengths such as 20, 24, 40, 45, 48 and 53 feet. Intermodal cargo containers have also been standardized in various widths. Typically, available cargo containers are either 96-inch (8xe2x80x2 0xe2x80x3) or 102-inch (8xe2x80x2 6xe2x80x3) in width. Today, intermodal containers are commonly available in the following dimensions: 20xe2x80x2Lxc3x978xe2x80x26xe2x80x3Hxc3x978xe2x80x20xe2x80x3W; 40xe2x80x2Lxc3x978xe2x80x26xe2x80x3Hxc3x978xe2x80x20xe2x80x3W; 45xe2x80x2Lxc3x979xe2x80x26xe2x80x3Hxc3x978xe2x80x26xe2x80x3W; and 53xe2x80x2Lxc3x979xe2x80x26xe2x80x3Hxc3x978xe2x80x26xe2x80x3W.
Each standardized cargo container has a different total load capacity. For example, the total load capacity of a typical 20-foot cargo container is approximately 52,900 pounds, while the total load capacity of a typical 40-foot or 48-foot cargo container is approximately 67,200 pounds.
The prior art has provided a variety of railroad freight cars adapted to carry intermodal cargo containers. Typically, such railcars are capable of carrying various configurations of different sized intermodal cargo containers. At times, a stacked arrangement of such cargo containers is employed.
One type of container car in use is referred to as a well car, since it has a container-receiving well between the wheeled trucks which support each end of the well car. The body of the car is generally at a low height, with containers in the bottom tier of a double-stacked container arrangement being supported approximately 10 inches above rail in a loaded car. Examples of such well cars are provided in U.S. Pat. No. 5,465,670, issued to Butcher on Nov. 14, 1995 and assigned to the present Applicant. Yet another railcar well design is disclosed in co-pending Canadian Patent Application Serial No. 2,175,440, filed in the names of Forbes and Coslovi on Apr. 30, 1996 and also assigned to the present Applicant. In order to transport as many combinations of standardized intermodal cargo containers as possible, the well of a typical well car is generally dimensioned to receive the longest and widest cargo containers commercially available.
During transport of intermodal cargo containers by rail, lateral and longitudinal forces act upon the cargo containers. These forces may be generated during switching operations and other car or train handling procedures. Typically, cargo containers are not latched to the car structure. Such containers simply sit on container support castings, which have guide blocks and locating cones welded to their flat top surfaces. A typical container support casting is illustrated in U.S. Pat. No. 5,501,556, issued to Butcher et al. on Mar. 26, 1996 and assigned to the present Applicant. The locating cones are each adapted to be received in a corresponding opening of a corner casting or a corresponding structural member of a container. The guide block serves to guide a container longitudinally during loading of the container into the well and onto the corresponding locating cone on the container support casting. Container support castings are conventionally located at the 40-foot corner locations of the well car floor. The practice to-date in this art is to have a plain support surface centrally within the railcar well, that is, a support surface which forms part of the well car floor and which is not provided with container support castings. Generally, cargo containers placed onto the floor structure of a well car are only restrained from longitudinal shifting by the container support castings.
When a second row of cargo containers is stacked onto a first row of containers in the well of a rail car, (i.e. when containers are xe2x80x9cdouble stackedxe2x80x9d) the top row of containers is secured to the bottom row of containers with connecting devices known to those in this art as inter-box connectors. These connectors join the upper four corners of the bottom row of containers to the lower four corners of the top row of containers and positively lock the containers in three directions. The lateral and longitudinal forces which act upon cargo containers during their transport results in the displacement or shifting of a container from an initial location in the container well to some other position due to the inertial or dynamic forces acting on the containers during transit. Where a container is loaded into an empty well car and the length of well portion of the well car exceeds the length of the container placed therein, longitudinal shifting of that container within the well can be expected. When a long container is stacked over two 20-foot containers, container pitching from longitudinal impacts to the well car is not an issue because the long container on top stabilizes the two lower containers. The lower 20-foot containers in such a configuration cannot readily pitch and lift off the trailing container support castings in a frontal collision of the railcar. However, the situation is quite different with double-stacked 20-foot containers. The high center of gravity of the containers, combined with their shorter 20-foot length, means that container pitching will be more prevalent in a double-stacked configuration and that the trailing ends of the containers may lift several inches off the container support castings in a frontal collision of the railcar. This increases the possibility that the trailing containers will therefore lift off the cones and slide forward, thereby impacting the lead containers. Similarly, pitching of the lead containers at the lead ends thereof will occur in rear collisions of the railcar.
To resolve the problems discussed above, a number of manually operable container stops have been disclosed which are located centrally within the railcar well and which are intended to prevent the longitudinal displacement or shifting of 20-foot containers in the well of the car. One such manually operable container stop is disclosed in U.S. Pat. No. 5,465,670, issued on Nov. 14, 1995 in the name of Butcher and assigned to the present Applicant. Another pivotable container stop is disclosed in Canadian co-pending application Serial No. 2,175,445 filed on Apr. 30, 1996 in the names of Butcher and Coslovi, which application has been assigned to the present Applicant. In these known container stops, an operator must manually activate the stop by unlocking a mechanism in the railcar sidewall to allow the stop to pivot into the well of the car. When so disposed, the stop prevents the longitudinal displacement or shifting of 20-foot containers within the well. If it is desired to employ the well of the railcar for a 40-foot container, the prior art manually operable stops must be retracted by an operator by pivotally moving the stop out of the well portion of the railcar and into its retracted position within the railcar sidewall. Otherwise, the known container stops would interfere with the loading of 40-foot or 48-foot containers.
In contrast to the known container stop devices, the present invention seeks to provide a container stop which is automatically activated to prevent the longitudinal shifting of containers in a well of a well car when containers of a certain predetermined length are loaded into the well. The container stop according to the present invention automatically retracts from the well floor structure when full-length containers, such as 40-foot to 53-foot containers are seated in the well. The automatically activated container stop preferably acts in conjunction with a container guide in the railcar sidewall which provides a protruding deflector to longitudinally deflect shorter containers, such as those having a 20-foot length, as they are lowered into the well, so that such containers are seated within the well of the railcar in such manner as not to each interfere with the operation of the retractable container stop.
According to a broad aspect of the present invention, there is provided an improvement for a railroad freight car for transporting intermodal cargo containers. The railroad freight car is of the type comprising spaced apart first and second side structures, opposed end structures and a floor structure, such that the side structures, end structures and floor structures together define a well for receiving a plurality of intermodal cargo containers. The well has a longitudinal direction substantially aligned with a direction of travel of the railroad freight car and a transverse direction substantially normal thereto. The floor structure of the railroad freight car comprises a container support within the well which provides a container support surface. The improvement according to a broad aspect of the present invention comprises a container stop that is provided with the container support, and has an extended position and a retracted position. The container stop is biased to the extended position, the extended position being defined by the container stop extending upwardly from the container support surface to present a stop surface within the well. The stop surface constitutes means for arresting the longitudinal translation of one of the intermodal cargo containers when same is located longitudinally aside the container stop and is seated on the container support surface. The retracted position of the container stop is defined by the container stop being retracted with respect to the container support surface when a cargo container is placed onto the container stop, such that the stop surface is not presented within the well.
With reference to preferred embodiments of the present invention, the container stop presents two stop surfaces within the well for arresting the longitudinal translation of two intermodel cargo containers when same are respectively located longitudinally on each side of the container stop and are respectively seated on the container support surface. A container guide is associated with the container stop. The container guide is provided in a side structure of the railcar. The container guide provides a deflector which extends within the well in the transverse direction. The deflector constitutes means for longitudinally guiding an intermodal cargo container within the well as said container is being placed therein. The deflector is dimensioned and positioned with respect to the container stop so as to prevent both of two intermodal cargo containers from seating onto the container stop together when each of the two intermodal containers is placed in succession within the well of the railroad freight car.
With reference to preferred embodiments of the present invention, the container stop may be supported-by a biasing component, with the biasing component being connected to the container support. The container stop and the biasing component may be received within a corresponding receptacle that is provided in the container support for slip fit engagement with the container stop.
Preferably, the container stop is substantially rectangular in cross-section, and provides a substantially planar top surface which is substantially co-planar with the container support surface when the container stop is in the retracted position. The container stop preferably provides two substantially planar and parallel side surfaces which are substantially vertically disposed with respect to the top surface and which respectively define the two stop surfaces of the container stop.
The biasing component for the container stop may be a coil spring. The container stop may be provided in the form of a hollow block.
The container guide preferably provides a bumper surface for laterally guiding an intermodal cargo container in the transverse direction within the well as the intermodal cargo container is being placed therein. The deflector is preferably mounted on the bumper surface and extends therefrom in the transverse direction.
The deflector may be provided with a pre-determined range of longitudinal translation with respect to the container stop. As well, the container guide is preferably removeable between a retracted position, wherein the container guide does not extend into the well of the railroad freight car, to an extended position, wherein the guide extends into the well so as to longitudinally and laterally guide the intermodal cargo container within the well as the container is being placed therein.
Preferably, the deflector comprises two substantially parallel and spaced apart side surfaces. Each of the side surfaces extends from the bumper surface in the transverse direction when the container guide means is in its extended position. The side surfaces each provide a supporting edge for two angled surfaces of the deflector, each of the angled surfaces extending respectively from the supporting edges of the side surfaces. The angled surfaces are joined at a common edge so as to define an inverted V-shaped projection which extends from the bumper surface in the transverse direction when the container guide is in the extended position thereof.
In a preferred embodiment, two container stops and two container guides are provided. The first of the two container stops is located substantially at the longitudinal midpoint of the well and adjacent the first side structure. The second of the two container stops is located laterally opposite and is aligned in the transverse direction with the first container stop and adjacent the second side structure. Each of the two container guides is associated with a respective container stop.